During the reproductive years, at least 1 in of every 2 or 3 women will experience bacterial vaginosis,  a vaginal discharge due to a shift in bacterial composition away from the normal flora.  Unfortunately even a single attack testifies to a woman’s susceptibility and suggests the likelihood of multiple recurrences over the upcoming many years to decades.

In many cases vaginal discharge heralds a recently acquired infection with yeast, Trichomonas, Chlamydia or other sexually transmitted condition.  However by far the most common culprit involves a dramatic fall in number and concentration of bacteria known as Lactobacilli with simultaneous overgrowth of a variety of less friendly organisms that generally represent only a small fraction of the flora normally present.

This condition known as Bacterial Vaginosis or simply BV confuses the medical profession as our understanding of its exact nature continues to evolve.  At present most authorities consider it a dysbiosis rather than a disease.  Since it’s not associated with inflammation of tissue, bacterial vaginitis would not be an appropriate name.


Actually the story began in 1780 when a bacterial organism was identified as the cause of fermentation of unpasteurized milk.  Known to affect humans only since the mid-1850s, it awaited Dr. Doderlein, a German gynecologist, to describe Lactobacillus in 1892 as a common constituent of the vagina.  Within several years doctors presented the first case of what we now refer to as BV.  In the early 1950s an army physician described another vaginal organism that several years later the Houston gynecologists Drs. Gardner and Dukes popularized as a frequent cause of this common vaginal abnormality.  As a tribute we refer to that bacterium as Gardnerella vaginalis.


Symptoms include an off white, typically thin homogeneous vaginal discharge without lumps that tends to be more noticeable after sexual relations and with hormonal fluctuation around the menses.  A characteristic feature involves a peculiar odor that many associate with the smell of rotten fish.  Neither redness of the genital area nor itchiness are common findings.  Similarly discomfort during sexual relations or while urinating are lacking.  Interestingly between 50-75% of women with typical bacterial changes of BV fail to demonstrate any hint of their condition.


Diagnosis of the original episode especially in the presence of characteristic complaints requires minimal evaluation.  Vaginal discharge may be easily examined under a microscope during the office visit.  Samples obtained by a swab reveal clue cells – nothing more than epithelial cells that line the vagina and cervix covered with rod shaped bacteria.  At the same time, other inflammatory conditions are excluded by the absence of white blood cells signaling an infection – perhaps with yeast or Trichomonads.

Adding a small drop of potassium hydroxide onto the microscope slide containing the discharge releases chemicals known as amines which provide the fishy odor and accounts for the positive “whiff test”.  Measuring the pH of the vaginal contents reveals it to be less acidic than normal.

Diagnosis seems well established but not assured in the presence of at least 3 of these 4 findings – discharge, clue cells, elevated pH, fishy odor.


Certain factors seem to elevate the likelihood of BV.  Obviously more sexual partners, either male or female, tend to increase the potential for problems, however BV may occasionally attack women who deny any prior any partner related sexual activities.  Commencing relations at a young age, those with new partners and women with a broader pattern of sexual engagement add to the potential for BV.  Other associations include recent antibiotics, cigarette smoking, obesity, previous pregnancy and contraception utilizing an intrauterine device.  The effect of oral contraceptives and depot injections of progesterone vary depending on a variety of circumstances.


Douching significantly alters the bacterial flora necessary to maintain vaginal health and must be discouraged almost under any circumstance.  Even the Department of Health and Human Services strongly cautions against this activity after sex, contact with lubricants or fecal exposure.  Additionally this activity may spread potentially harmful microbial organisms through the cervix and into the uterus or fallopian tubes.

Also discouraged are the numerous feminine hygiene products so readily available in most grocery and drug stores or online.  These pads, powders, sprays, deodorants, soaps, washes, fragrances and towlettes regularly disrupt the microflora and may predispose to BV.  Similarly experts suggest showering rather than bathing and basically condemn bubble baths as too dangerous to vaginal health.


Whether to consider BV a sexually acquired condition requires a very nuanced response.  Experts vacillate on their answer as more information regarding BV becomes available.  At present it seems the Lactobacilli which constitute more than 90-95 of normal vaginal bacteria gain entrance from the nearby colorectal area.  More importantly the Gardnerella vaginalis organisms probably represent contamination via sexual relations.

Depending on the peculiarities of the specific Gardnerella genotype, they may establish and live forever in a biofilm firmly adherent to the walls of the vagina.  Once established this biofilm protects the organisms from both oral and topical antibiotics.  In this regard the process bears some superficial similarity to that of the herpes virus – once you become infected, recurrences occur periodically at irregular intervals often for no obvious reason with the inciting organism persisting forever in the body.


Susceptibility to BV to some degree depends on a wide range of poorly understood mechanisms including genetics, biological factors, innate and acquired immunity, sexual networking and ethnicity.  Risk among African-American women seems greater than in Caucasian and Hispanic women with Asians appearing least likely to experience the condition.


In most non-African-American women different species of lactobacilli predominate existing in relative harmony with a relatively small concentrations of Gardnerella, Prevotella, Atopobium, Enterococcus, Bacteroides, Peptostreptococcus, Fusobacteria and Mobiluncus bacteria.  Most of these grow anaerobically – in the absence of oxygen.  In the absence of some growth stimulus, these non-lactobacilli fail to make their appearance known.

Many different species of Lactobacilli exist such as L. crispatus, L. iners, L. gasseri and L. jensenii among others.  These predominate in a healthy vagina and produce lactic acid, hydrogen peroxide and bacteriocins all of which maintain normal homeostasis, prevent growth of other organisms and protect against disease.  Some of these Lactobacilli may be responsible for maintaining an adequate mucus layer necessary to protect the relatively weak epithelial lining of the vagina.  These Lactobacilli predominate in Caucasians, Hispanics and Asians but appear much less commonly in African-American women.

Gardnerella may be present in the vagina, mouth, urethra and rectum and seems apt to colonize the penis especially in uncircumcised men.  While this anaerobic bacteria tends to be present in most women, the concentration usually appears quite low.  In a previous era it was thought to be the main infecting organism in BV.  Now its importance appears to revolve around its ability to produce a biofilm.



while unknown prior to 1978 now seem to be associated with an enormous list of chronic infectious conditions that characteristically resist antibiotic elimination.  These biofilms create havoc when they form on a hip or knee implant, an artificial heart valve, around the capsule following breast augmentation and of course the vaginal wall in BV.  Biofilms are responsible for periodontal disease as well.

Not all bacteria appear capable of forming biofilms, but Gardnerella remains well known in this capacity and in this situation the biofilm appears unusually thick and dense.  Once it contacts the mucus layer it forms an adherent membrane and begins secreting a variety of substances that in effect glue it to the vaginal wall.  The Gardnerella in effect creates its own home where it and other anaerobic bacteria grow and prosper out of reach of protective substances manufactured by the lactobacilli and the body’s immune system.

Even more startling Gardnerella in the biofilm seem capable of altering its own genes allowing the bacteria to express pumps designed to expel any antibiotic that might harm them.  Actually two different populations of Gardnerella exist: one loosely adherent to the vaginal wall and another encased in the thick biofilm.  Antibiotics may actually create problems since they affect only the loosely adherent bacteria and in the process further disrupt the situation.


Under normal conditions harmony rules.  For unknown reasons the Lactobacilli content declines precipitously with an equal and dramatic increase in Gardnerella, Prevotella and Bacteroides.  The reservoir for these other organisms appears to be the biofilm or less likely recolonization from the rectum.  The precise triggering event may be sexual activity, menstruation, hormonal fluctuation, stress, antibiotics for another purpose or a host of factors yet to be determined.

Although BV itself seems relatively innocuous with many episodes lacking any symptoms, the disruption of normal vaginal microbial flora significantly impacts on a woman’s susceptibility to a variety of issues.  As with the colon where there are “good” and “bad” bacteria, an analogous situation exists in the vagina.  With reduction in the “good” Lactobacilli, the mucus layer of the vagina loses its ability to prevent more noxious, disease causing bacteria and viruses from colonizing the area or gaining entrance to the bloodstream.


Women with active BV not only seem inordinately susceptible to infection with the HIV/AIDS virus, but shedding of the virus increases together with a greater likelihood of passage to the male partner.  BV also increases the risk of acquiring gonorrhea, Chlamydia, genital herpes and pelvic inflammatory disease more commonly referred to as PID.  Additionally women with BV experience a 3-5 fold increase in risk of spontaneous pregnancy loss in the first trimester, preterm delivery and premature rupture of the membranes.  BV also greatly enhances the potential for infection after cesarean section and in the uterus – post-partum endometritis.  Fortunately in spite of these added risks, most women with BV suffer no adverse consequences beyond the typical vaginal discharge.


Lots of therapies but none are curative.

Treatment leaves a lot to be desired changing relatively little since the late-1970s.  Antibiotics either taken by mouth or inserted as gels or creams into the vagina remain standard.  Metronidazole and clindamycin containing preparations remain cost effective with newer relatives offering more convenience at a greater price but fail to significantly improve the outcome.  None of these medicines seem capable of eradicating organisms within the biofilm.

As a result of the biofilm, the recurrence rate may be as high as 80% with many women suffering multiple attacks each year and in some unfortunate individuals episodes may appear monthly.  In appropriate circumstances suppressive treatment for 3-6 months may be necessary.  Therapy may benefit pregnant women by reducing the chance of premature labor and minimizing the odds of infection after cesarean section, hysterectomy or subsequent IUD insertion.

At present evidence does not exist to suggest treatment of the male consort.


A variety of novel therapies may ultimately prove beneficial.  Although widely discussed, probiotics remain of uncertain value.  Assuming organisms present in the pills or yogurt taken by mouth actually contain sufficient quantities of the proper type, they must survive the stomach acid and intestinal enzymes to arrive intact in the colon.  From there they must gain entrance into the vagina in numbers capable of overcoming the generally inhospitable nature of this tissue.  After all the microbial landscape of the vagina  establishes itself relatively early in life and tends to jealously guard it’s territory against unwelcome organisms.

Prebiotics, in this case sugars or sucrose preferred by the Lactobacilli potentially offer another avenue to encourage growth of friendly organisms.  Ongoing and promising research may allow insight into methods capable of disrupting the biofilm.  Natural antimicrobials, plant derived compounds and investigations into topical antiseptics as opposed to antibiotics may ultimately prove advantageous.


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